1. Field of Use
The invention pertains to injection molding machines of the type in which molten material is drawn into a shot tube from a reservoir and a shot tip is powered through the shot tube to push the molten material into the die cavity of the machine. In conventional machines, these shot tips wear out rapidly if there is any side thrust or bending moment between them and the shot tube. These undesirable forces are developed by misalignment due to the close tolerances which must be held between the various parts of the machine and which result in flexing due to high compressive stresses, and the large number of severe impacts during the injection strokes. These misalignment problems exist between the shot tube and the shot tip as they are being telescoped together and result in rapid wearing of the shot tips due to the side thrust or bending action imposed upon them.
2. Description of the Prior Art
Examples of injection molding machines of the type to which the present invention generally relates are shown in the U.S. Pat. No. 2,741,006, issued Apr. 10, 1956 and entitled "Means for Delivering Charges of Molten Metal;" U.S. Pat. No. 1,994,824, issued Mar. 19, 1935 and entitled "Die Casting Machine;" U.S. Pat. No. 2,839,800, issued June 24, 1958 and entitled "Method of and Apparatus for Damping Shocks;" U.S. Pat. No. 3,171,172, issued Mar. 2, 1965 and entitled "Injection Pistons for Pressure Casting Machines;" and U.S. Pat. No. 2,656,576, issued Oct. 27, 1953 and entitled "Die Casting Machine."